Objectives: The purpose of this study was to evaluate the long-term prognostic value of ST segment depression on the electrocardiogram (ECG) in patients with acute myocardial infarction.
Background: The prognostic importance of ST segment depression on the ECG has been studied in small groups of patients with infarction, but larger numbers are needed.
Methods: Coronary care unit ECGs of 1,234 patients who survived the coronary care unit with acute Q wave (n = 896) or non-Q wave (n = 338) myocardial infarction were analyzed for the presence of ST segment depression. Patients were followed up for up to 4 years.
Results: ST segment depression was present in 607 patients. Those with ST segment depression had a 1-year mortality rate of 10.3% compared with a rate of 5.6% for those without ST segment depression (p = 0.002). This effect was seen in both the Q wave and non-Q wave subgroups. Of the 437 patients with anterior ST segment elevation, those with ST segment depression in other regions had a 13.6% 1-year mortality rate compared with a rate of 6.9% for those with no ST segment depression (p = 0.0005). Of the 514 patients with inferior ST segment elevation, those with ST segment depression in other leads had an 11.0% 1-year mortality rate compared with a 1.8% rate for those with no ST segment depression (p = 0.0001). The Cox proportional hazards model showed that ST segment depression was an independent predictor of mortality over the follow-up period.
Conclusions: ST segment depression on the admitting ECG in patients with acute myocardial infarction is a predictor of increased mortality in the year after infarction.